共查询到20条相似文献,搜索用时 78 毫秒
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引入了T_λ算子,基于此算子,对模糊集的凸和拟凸的一些性质进行了研究,得出了一些结论。对模糊集的凸和拟凸的概念进行了拓展,引入了半凸模糊集,半拟凸模糊集,研究了半凸模糊集和半拟凸模糊集的性质。 相似文献
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基于GRA-DEA模型的有关农民收入的九城市的评价 总被引:1,自引:0,他引:1
王有文 《数学的实践与认识》2018,(6)
有关农民收入,文章以山西省九个城市为例进行了评价.首先用灰色关联分析法分析了2016年这些城市的有关数据,筛选出影响农民收入的主要因素;其次构建了指标体系,利用数据包络分析法对有关农民收入九个城市进行了DEA有效性评价;再次对非DEA有效的城市,借助投影公式探索了改进方法;最后得出了九城市分为两类的结论,提出了针对性的建议. 相似文献
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由于自动控制理论提出了二阶微分方程的零解的全局稳定性,引起了不少数学工作者的研究,H.H.研究了方程组(1,1),得到了零解为全局稳定的充分条件,本文采用定性方法,研究了方程组(1,1)的零解为全局稳定的必要条件,并削弱了[1]中的充分条件,从而得到方程组(1,1)的零解为全局稳定的充要条件(定理 3——5).同时还研究了方程组(2,1)的零解为全局稳定的充要条件(定理6). 相似文献
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张肇濠 《数学的实践与认识》1979,(4)
本文在[1]的基础上,引进了递差方阵 D,给出了 Vandermonde 型阵 V_m 的逆阵的显示式,从而得到了方程组(1),(1′)的可供直接计算用的用三角阵表示的解的公式.此外,还得到了包括[2]的化(1′)为三角形方程组的结果. 相似文献
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In this article, we study positive solutions to the system{A_αu(x) = C_(n,α)PV∫_(Rn)(a1(x-y)(u(x)-u(y)))/(|x-y|~(n+α))dy = f(u(x), B_βv(x) = C_(n,β)PV ∫_(Rn)(a2(x-y)(v(x)-v(y))/(|x-y|~(n+β))dy = g(u(x),v(x)).To reach our aim, by using the method of moving planes, we prove a narrow region principle and a decay at infinity by the iteration method. On the basis of these results, we conclude radial symmetry and monotonicity of positive solutions for the problems involving the weighted fractional system on an unit ball and the whole space. Furthermore, non-existence of nonnegative solutions on a half space is given. 相似文献
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Reza Mazrooei-Sebdani 《Communications in Nonlinear Science & Numerical Simulation》2012,17(10):3857-3865
Consider the following system of rational equations containing quadratic termsChaos in the sense of Li–Yorke is considered. This is based on the Marotto’s theorem via obtaining a snap-back repeller. In fact, first in a special case when , we show that origin is a snap-back repeller and so the system has chaotic behavior in the sense of Li–Yorke under some conditions. Then in a more general case, we prove that existence of chaos in the sense of Li–Yorke for the above system. 相似文献
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We consider the system of nonlinear wave equations with initial and Dirichlet boundary conditions. Under some suitable assumptions on the functions, , , , parameters and the initial data, the result on blow-up of solutions and upper bound of blow-up time are given. 相似文献
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We consider the fractional Hartree equation in the -supercritical case, and find a sharp threshold of the scattering versus blow-up dichotomy for radial data: If and , then the solution is globally well-posed and scatters; if and , the solution blows up in finite time. This condition is sharp in the sense that the solitary wave solution is global but not scattering, which satisfies the equality in the above conditions. Here, Q is the ground-state solution for the fractional Hartree equation. 相似文献
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